Azaphenalene Phthalocyanines: Phthalocyanine Analogues with Six‐Membered‐Ring Units Instead of Five‐Membered‐Ring Units

Abstract

Mixed-condensation reaction of 1,8-naphthalenedicarbonitrile and a 4,5-disubstituted phthalonitrile provided a series of phthalocyanine (Pc) analogues with azaphenalene (AP) moieties in place of the isoindole moieties. Monosubstituted species, APPc, and the two structural isomers of disubstituted species, adj-AP(2)Pc and opp-AP(2)Pc, were successfully isolated by gel-permeation chromatography on HPLC apparatus. Their structures were elucidated by (1)H NMR spectroscopy and X-ray crystallographic analysis. Replacement of the isoindole moieties with azaphenalene moieties created six-membered-ring units in the core and caused distortion of the molecular structures. The Q-band absorption shifted to the red upon an increase in the number of azaphenalene units; the shape of the absorption spectra depended on the molecular symmetries. APPc and opp-AP(2)Pc showed a large splitting of the Q band, whereas adj-AP(2)Pc exhibited a single broad Q band. These changes in the absorption spectra, as well as the unique electronic structures, are discussed in detail, based on magnetic circular dichroism spectra, electrochemical measurements, and density functional theory calculations.

Core-Modified Phthalocyanines and Subphthalocyanines: a Synthetic Strategy towards Core-Modification and Novel Properties Arising from the Inner Ring-Expansion

“…[10,16] A mixed condensation reaction with o-phthalonitrile in the presence of nickel acetate and hydroquinone, and in the absence of solvent at 300 °C has provided core-modified Pcs with a six-membered ring embedded in an azaphenalene unit, which is therefore referred to as azaphenalenephthalocyanine (APPc) (Scheme 1, conditions a). In addition to Pc 1a and APPc 2a obtained in the yields of 9 and 26 %, respectively, disubstituted species with adjacently arranged azaphenalene units (adj-AP 2 Pc, 3) were also obtained in 13 % yield.…”

“…[10,11] The crystal structure of APPc 2b has exhibited a rather planar structure with a pyridine axial ligand, in which the azaphenalene unit was slightly tilted by 3.3° from the mean plane of the four zinccoordinating nitrogen atoms (4N mean plane) ( Figure 5). The central zinc ion was deviated by 0.33 Å from the 4N mean plane.…”

“…The thermal ellipsoids were scaled to the 50 % probability level. Hydrogen atoms and p-tert-butylphenoxy substituents were omitted for clarity in the side view (adapted from the reference [10] with permission from Wiley). and side view (bottom).…”

“…and side view (bottom). Hydrogen atoms were omitted for clarity (adapted from the reference [10] with permission from Wiley).…”

“…Using 1,8-naphthalenedicarbonitrile and 2,2'-biphenyldicarbonitrile as key precursors, coremodified Pc analogues with six-and seven-membered ring units, which retained Pc-like macrocyclic conjugated systems, were successfully synthesized. [10,11] By applying this synthetic strategy to subphthalocyanine (SubPc), which is a ring contracted Pc analogue, core-modified SubPc analogues were also synthesized. [12][13][14] In this microreview, the contribution of the authors in the synthesis of core-modified Pcs and SubPcs as well as the their unique properties arising from the core-modification are surveyed.…”